Clear SQL Azure execution plan / query cache
ALTER DATABASE SCOPED CONFIGURATION CLEAR PROCEDURE_CACHE is designed to help wit this problem.
This is closest to the DBCC FREEPROCCACHE you have in SQL Server but is scoped to a database instead of the server instance. This does not prevent caching of query plans - it just invalidates the current cache entries.
Please note that the query store is there to help you in SQL Azure (on-by-default). It stores a history of plan choices and plan performance (per-plan). So, if you have a prior plan that performs better available in the history of your application, you can force it using SSMS if you'd prefer to have the query optimizer pick this plan each time your query compiles. One common reason for what you are seeing is parameter-sensitivity in the plan choice where the optimizer will use the passed parameter value to try to generate the query plan, assuming it is representing a common pattern when you run that query. If that value is actually not close to a common value (in terms of how frequent it is in the table), then you can sometimes compile and cache a plan that is not better on average for your application.
Query store has an overview here:https://docs.microsoft.com/en-us/sql/relational-databases/performance/monitoring-performance-by-using-the-query-store?view=sql-server-2017
Note that SQL Azure also has an automated mechanism to try forcing prior plans if it notices a performance regression. It is somewhat conservative, however, so it may not kick in for every single regression until it sees an obvious pattern over time. So, while you can force things in SSMS, you can also potentially just wait (assuming this is the issue you were seeing)